Exemplary embodiments of the invention relate to a transceiver element for an active, electronically controlled antenna system.
Active, electronically controlled antenna systems consist, in principle, of the three subsystems:                A. RF splitter and combiner system (also referred to as RF supply system),        B. active transmitter modules, receiver modules or combined active transmit/receive modules, also referred to as T/R modules, arranged between the antenna-side outputs of the RF supply system and the antenna elements, and        C. the antenna elements which, together, cover a common antenna aperture.        
A typical antenna system such as this contains a multiplicity of transmitter-antenna and/or receiver-antenna elements arranged linearly or in a matrix, which are only at a short distance apart from one another, usually a spacing of approximately λ/2, wherein λ is the transceiver wavelength. A transceiver module is directly coupled to each of said transmitter-antenna and/or receiver-antenna elements.
In general, a transceiver module contains a transmit path with an RF transmission amplifier (also referred to as power amplifier) and a receive path containing at least one low-noise amplifier. In addition, at least transceiver changeover switches and an amplitude and phase adjuster are present in the transceiver module.
Amplitude and phase adjusters are used, first, to compensate the electrical manufacturing tolerances present between the individual transceiver modules and, secondly, to adjust in a predefinable manner the amplitude and phase differences for the transmission and/or reception waves in the case of adjacent transmitter-antenna and/or receiver-antenna elements connected to the transceiver modules. Hence, electrical adjustment and/or spatial pivoting of the transmit/receive radiation pattern of the antenna is possible.
One problem of known antenna systems is that the amplitude and phase adjusters can work reliably and effectively only within a predefined restricted frequency band. Outside of this frequency band to which the amplitude and phase adjuster of a transceiver module is tuned, meaningful signal evaluation is not possible. In the case of an antenna system with fixedly installed transceiver modules, it is not possible to change the frequency band.
German patent document DE 696 30 512 T2 describes a switchable power amplifier for transmitting RF signals at two different frequencies and two different output powers by temporal synchronization of four switches. For this purpose, two single-pole changeover switches are provided, the central connections of which are connected to one another via two further single-pole changeover switches.
A transceiver element which operates at the RF level and is used in electronically phased array antennas is known from European patent document EP 0 762 541 A2. The transceiver element has a transmit path, a receive path and two single-pole changeover switches with a common central connection and two connections for changing over between the transmit path and the receive path. Furthermore, the transceiver element comprises a multiple-throw switch, an amplitude adjuster and a phase adjuster.
U.S. Pat. No. 5,446,464 discloses a transceiver element a transmit path, a receive path with two single-pole changeover switches the central connections of which are connected to one another via an amplitude adjuster and a phase adjuster. The frequency band of the transceiver element is restricted to two narrow band frequency ranges of 5-6 GHz and 9.5-10.5 GHz.
Exemplary embodiments of the present invention are directed to a transceiver module with which it is possible to achieve reliable and effective signal evaluation over a frequency band which is of any width.
The transceiver element according to the invention for an active, electronically controlled antenna system comprises a transmit path, a receive path and single-pole changeover switches with a common central connection and two connections for changing over between the transmit path and the receive path, wherein a plurality of amplitude adjusters and a plurality of phase adjusters are arranged between the common central connections of a first and a second single-pole changeover switch. Single-pole changeover switches are also referred to as single-pole double-throw (SPDT) switches.
The invention is distinguished in that single-pole multiple-throw switches with a common central connection and a number N of connections A1, . . . , N are present, wherein the common central connection of the first or second single-pole changeover switch is connected to the common central connection of a first or a second single-pole multiple-throw switch and an amplitude adjuster AS1, . . . , N and a phase adjuster PS1, . . . , N are switched in each case between each connection A1, . . . , N or connection B1, . . . , N of the number N of connections of the first and second multiple-throw switches.
In this case, the amplitude adjusters AS1, . . . , N and a phase adjuster PS1, . . . , N form in each case amplitude adjuster and phase adjuster pairs that can be actuated by the two single-pole multiple-throw switches. Depending on the application of an antenna system, the properties of any single amplitude adjuster and phase adjuster pair can be used.
In one embodiment of the invention, the first and the second single-pole multiple-throw switches are interconnected such that the changeover of the first and the second single-pole multiple-throw switch to the amplitude adjuster AS1, . . . , N and the phase adjuster PS1, . . . , N takes place synchronously. As a result, it is ensured that each multiple-throw switch switches in each case to the same amplitude and phase adjuster pair in the event of a changeover of the first and second single-pole multiple-throw switches. Expediently, a control circuit is provided for this purpose.
In another embodiment of the invention, the amplitude adjusters AS1, . . . , N and phase adjusters PS1, . . . , N between the connections A1, . . . , N and B1, . . . , N of the first and second multiple-throw switches are in each case adjusted to different frequency bands. Expediently, the individual amplitude and phase adjuster pairs can be tuned to, for example, the L band, S band, C band, X band, Ku band, K band or Ka band, or partial bands therefrom or combinations of the bands and/or partial bands mentioned above. Of course, the amplitude and phase adjuster pairs can also be tuned to frequency bands outside of the stated frequency bands. As a result, it is possible to specify a multi-band antenna system.
In another embodiment of the invention, the number N of connections A1, . . . , N and B1, . . . , N of the first and second single-pole multiple-throw switches is 2, 3, 4, 5, 6 or 7. Expediently, the number N of connections A1, . . . , N or B1, . . . , N of the first or second single-pole multiple-throw switches is 4, that is to say N=4, and so a single-pole four-throw (SP4T) switch known from the prior art can be used. SP4T switches known from the prior art have low losses.
The antenna system according to the invention is distinguished in that the spacing of the transceiver elements is less than λ/2, wherein λ is the wavelength of that band with the highest frequency that is used in any of the transceiver elements. This means that, in the case of an antenna system with, for example, two SP4T multiple-pole switches and amplitude and phase adjuster pairs tuned to the S band, C band, X band and Ku band, the spacing of the individual transceiver elements in the antenna system is geared to the highest frequency in the Ku band.
In an embodiment of the antenna system according to the invention, a controller is present for controlling the first and second single-pole multiple-throw switches. As a result, it is ensured that each multiple-throw switch switches in each case to the same amplitude and phase adjuster pair in the event of a changeover of the first and second single-pole multiple-throw switches.
In another embodiment of the antenna system according to the invention, a controller is present for controlling the single-pole changeover switches for changing over between transmit and receive path.
In another embodiment of the antenna system according to the invention, a controller is present for controlling the amplitude adjuster and phase adjuster pairs in order to adjust the respectively desired amplitude or phase.
In the figures, identical components and identical functions are denoted by identical reference signs in each case.